Macular dystrophy is a term applied to a heterogeneous group of diseases that collectively are the cause of severe visual loss in a large number of people. A common characteristic of macular dystrophy is a progressive loss of central vision resulting from the degeneration of photoreceptor cells in the retinal macula. In many forms of macular dystrophy, the end stage of the disease results in legal blindness. More than 20 types of macular dystrophy are known: e.g., age-related macular dystrophy, Stargardt-like dominant macular dystrophy, recessive Stargardt's disease, atypical vitelliform macular dystrophy (VMD1), Usher Syndrome Type 1B, autosomal dominant neovascular inflammatory vitreoretinopathy, familial exudative vitreoretinopathy, and Best's macular dystrophy (also known as hereditary macular dystrophy or Best's vitelliform macular dystrophy (VMD2). For a review of the macular dystrophies, see Sullivan & Daiger, 1996, Mol. Med. Today 2:380–386.
Stargardt-like dominant macular dystrophy (also called autosomal dominant macular atrophy) is a juvenile-onset macular degeneration. Patients afflicted with this disease generally have normal vision as young children, but during childhood, visual loss begins, which rapidly progresses to legal blindness. Clinically it is characterized by the presence of an atrophic macular lesion with sharp borders and is often associated with yellow fundus flecks. The pathological features seen in Stargardt-like dominant macular dystrophy are in many ways similar to the features seen in age-related macular dystrophy (AMD), the leading cause of blindness in older patients in the developed world.
AMD is an extraordinarily difficult disease to study genetically, since by the time patients are diagnosed, their parents are usually no longer living and their children are still asymptomatic. Thus, family studies which have led to the discovery of the genetic basis of many other diseases have not been practical for age-related macular dystrophy. As there are currently no widely effective treatments for AMD, it is hoped that study of Stargardt-like dominant macular dystrophy, and in particular the discovery of the underlying genetic cause of Stargardt-like dominant macular dystrophy, will shed light on age-related macular dystrophy as well. A significant proportion of the AMD cases is caused by recessive mutations in the recessive Stargardt disease gene. (Allikmets, et al 1997 Science 277:1805–1807).
It seems reasonable to suggest that mutations within the disease gene responsible for Stargardt-like dominant macular dystrophy which closely resembles the recessive Stargardt disease may be responsible for the significant proportion of AMD cases. It would be desirable to characterize the gene responsible for this disease in order to have a better understanding of this disease and to elucidate its potential role in other forms of macular degeneration.